Add an Iterative approach for PreOrder Traversal of a Binary Tree in C++

[khagapati-bagh]

Add preorder traversal iterative approach for a binary tree in C++ inside C++/DataStructure/Tree directory and name the file as preOrderTraversalIterative.cpp. Please follow the contribution guidelines without this your code will not be accepted.

[akshaydhayal]

@khagapati-bagh Hey, can you assign this task to me?

[harmankaler2000]

Hey! @khagapati-bagh can I work on this issue!

[khagapati-bagh]

@khagapati-bagh Hey, can you assign this task to me?

Hi @akshaydhayal, Yes you can work on this issue, make sure you follow contribution guidelines.

[khagapati-bagh]

Hey! @khagapati-bagh can I work on this issue!

Hi @harmankaler2000, If you want you can work on #71 issue. Please reply, so that I can assign, if you are interested then.

[akshaydhayal]

#75 @khagapati-bagh Please review this PR.